Trump administration officials on Sunday made it clear that Russia must end their support for the Syrian government or its relationship with the United States will continue to dwindle, according to the Washington Post, providing a basis for what talks between Moscow and Washington will resemble this week when Secretary of State Rex Tillerson visits Russia. Officials have said that Russia bears at least some responsibility for last week’s chemical attack that was allegedly carried out by Syrian President Bashar al-Assad.

“I hope Russia is thinking carefully about its continued alliance with Bashar al-Assad, because every time one of these horrific attacks occurs, it draws Russia closer into some level of responsibility,” Tillerson said on ABC’s “This Week.”

On Monday, the Kremlin said President Vladimir Putin is not currently planned to meet with Tillerson who is scheduled to only be meeting with Russia’s foreign minister.

“We have not announced any meetings. A meeting with Tillerson is currently not on the president’s schedule,” Putin’s spokesman, Dmitry Peskov, told reporters, according to the Post.

But last month, John Teft, the American ambassador to Russia, stated that Tillerson was likely to meet with Putin “in the near future,” according to the Associated Press.

Peskov explained to reporters that “as far as I understand, [Tillerson] is coming and will have negotiations with our foreign minister,” noting that if plans for a scheduled meeting arise, the public will be informed “appropriately” according to the Washington Post.

The U.S. has not found any conclusive evidence that Russia was directly involved with, or even knew ahead of time, about last week’s chemical attack, but national security adviser H.R. McMaster said that questions about the Russian’s prior knowledge deserve answers.

“I think what we should do is ask Russia, how could it be, if you have advisers at that airfield, that you didn’t know that the Syrian air force was preparing and executing a mass murder attack with chemical weapons?” McMaster told Fox News.

The Washington Post reports:

The fallout from the Syrian regime’s use of chemical weapons against civilians, plus the U.S. missile strike that came in retaliation for it, adds strain to a rocky relationship that is at its lowest point in decades. A host of issues are responsible, topped by Russian interference in the U.S. presidential election and Moscow’s support for separatists in Ukraine, and have prompted U.S. and European sanctions. These topics have now been overshadowed by last week’s missile strike.

The Russians had hoped that relations with the United States might improve under President Trump, who expressed admiration for Putin during the campaign. Tillerson’s nomination and ­confirmation as secretary of state also raised prospects. given the former ExxonMobil executive’s experience negotiating a major deal with Rosneft, the state-controlled oil giant.

While attending a G7 meeting in Italy on Monday morning, Tillerson was a participant in a wreath-laying ceremony at a memorial to 560 villagers killed by Nazis in 1944. Following the commemoration, Tillerson compared the situation to contemporary events unfolding in Syria.

“We rededicate ourselves to holding to account any and all who commit crimes against the innocents anywhere in the world,” Tillerson stated, according to the Washington Post. Though Tillerson was originally not expected to make an appearance, he reportedly wanted to stand with the foreign ministers of Italy, Germany and the European Union. “This place will serve as an inspiration to us all.”

Tillerson is due to arrive in Russia late into Tuesday, where he will subsequently meet with Russia’s Foreign Minister Sergei Lavrov, in his first visit as secretary of state.